WTF is RPE?

For a long time, I nodded along whenever someone said “RPE” like I knew exactly what they meant.

I’d been training for years, I could tell you my 3RM or 1RM on all my key lifts. In my notes app I’d track when I felt I’d maxed out a lift in a session using the skull emoji. That was my simplified version of what I thought RPE was for.

It wasn’t until I started training more seriously, speaking with coaches and friends that I realised that I needed to be tracking my effort (and progress) better.

So I googled what RPE actually was, and I thought I finally understood it. But it wasn’t until I started reading more articles on it that I realised I was still tracking it wrong — what I thought was a 9 or 10 usually wasn’t.

So, WTF is RPE? Here’s the simple definition so you don’t make the same mistake I did. RPE stands for Rate of Perceived Exertion — a 1-to-10 scale for how hard a set actually felt, with 10 being “I could not have done one more rep” and lower numbers meaning you had reps left in the tank. That’s it. That’s the whole concept. Personally I like to do it as a count of how many more reps I could have done. That gives me a more specific number so I can tell the difference between what an 8 and a 9 is for me.

Why this number matters more than it sounds like it should

Have you ever looked back at your last few sessions and wondered: am I actually getting better at this? Looking at weights alone often isn’t enough to tell you — especially if you aren’t training to failure.

The same weight doesn’t feel the same every day. 135 pounds on a good night’s sleep, fed, rested, and motivated is a different task than 135 pounds after a bad week, even though it’s the identical number on the bar. If you only ever track the weight, you’re missing half the picture — you don’t know whether that 135 was easy or a genuine grind.

RPE is how you capture how the lift actually felt. Two sessions with the same weight and reps can be completely different training stimuli depending on how much you had left afterward, and RPE is the tool for writing that down instead of just remembering (badly) how it felt.

The scale, actually explained

The version most lifters and coaches use today is built around reps in reserve (RIR) — literally, how many more reps you think you could have done with good form before failing. A 2016 study that developed this specific scale tied each RPE number to a concrete RIR description rather than a vague feeling, which is what makes it useful instead of just vibes with a number attached:

RPE	What it means
10	Max effort. Could not do another rep or add any weight.
9	1 rep left in the tank.
8	2 reps left.
7	2–3 reps left.
5–6	4–6 reps left — solid working effort, not close to failure.
Below 5	Warm-up territory. Could do this for a while.

A real RPE 10 is rare and it should be, because if every set is a 10, you have no way to tell your hardest day from your normal one. You know the Friends episode where Ross is dragging a couch up the stairwell, absolutely losing it, screaming “PIVOT!”? That’s an RPE 10. Most working sets should live in the 7–9 range — calm enough that nobody on the stairwell needs to hear about it. Save the 10s for when you actually mean it.

RPE isn’t the same as “how hard did that feel”

This is where most confusion actually comes from — RPE gets used interchangeably with general exhaustion, and it isn’t the same thing. We’ve written before about why “how wrecked you feel” is a bad proxy for whether a session worked — the same logic applies here. RPE isn’t asking “how hard was my whole workout,” it’s asking “how many more reps did I have in this specific set, at this specific weight.” It’s set-by-set, not vibes-for-the-day.

That distinction matters because it’s what makes RPE trainable and comparable over time. “I felt tired” tells you almost nothing useful three weeks from now. “That set was an RPE 8” is a specific enough data point to actually compare against the RPE 8 you logged for the same lift last month — and if the same weight and reps have dropped from an 8 to a 6, that’s real, measurable progress, not a feeling.

You’re probably not as accurate as you think — and that’s normal

Even experienced lifters aren’t great at this, so you don’t beat yourself up over it. A 2020 review looking at how well trained lifters predict their actual proximity to failure found that people consistently underestimate how many reps they actually have left — by about two reps, on average — meaning most of us stop further from true failure than we think we’re stopping. Experience helps (the same research backing the RIR scale found trained lifters rate more accurately than untrained ones), but nobody’s perfectly calibrated, and expecting to be is setting yourself up to feel like you’re bad at something everyone’s a little bad at.

The fix isn’t “try harder to be accurate.” It’s consistency — rate the same way, honestly, every session, and let the trend do the work instead of demanding perfect precision from any single number.

Personally, I find taking a set to actual failure every so often is the best way to recalibrate what my own RPE numbers really mean. As I go through a session, I’ll sometimes go back and edit the RPE on earlier sets once I realise I actually had a lot more left in the tank than it felt like at the time.

How to actually use it

Rate the set, not the workout. RPE is per-set, tied to a specific weight and rep count — not a general “how did today go” score.

Be honest, not aspirational. Rating everything a 9 because that feels like the “correct” answer defeats the purpose. The whole value is in the number being real enough to compare against next time.

Log it every time, not just on hard days. A trend needs data points on the easy sessions too — that’s exactly where you’ll first notice a weight getting easier, per the session-RPE tracking discussed above.

Expect to get better at it, not perfect. You’ll under- and overshoot sometimes. That’s the norm, not a sign you’re doing it wrong.

The bottom line

RPE is just a 1-to-10 answer to one question: how many more reps did you have left in that set? It matters because the weight on the bar alone doesn’t tell you whether a session was easy or a grind, and tracking that honestly, set after set, turns “I think that felt about the same” into something you can actually compare over time. You won’t rate it perfectly, and you don’t need to — you just need to do it consistently enough for the trend to mean something.

Sources

• Zourdos MC, Klemp A, Dolan C, et al. Novel Resistance Training-Specific Rating of Perceived Exertion Scale Measuring Repetitions in Reserve. Journal of Strength and Conditioning Research, 2016.
• Armes C, Standish-Hunt H, Androulakis-Korakakis P, et al. “Just One More Rep!” – Ability to Predict Proximity to Task Failure in Resistance Trained Persons. Frontiers in Psychology, 2020.